• Title/Summary/Keyword: YBCO thick film

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Surface Properties of Superconducting Thick Film with Suspension Solution added with Polymer (폴리머를 첨가한 현탁용매에 따른 초전도 후막의 표면특성)

  • 소대화;이영매;임병제;김태완;전용우;코로보바나탈리아
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.11a
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    • pp.503-506
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    • 2000
  • YBCO superconducting thick films were prepared on Ag wire by electrophoresis in acetone and ethanol with chemically modified suspension. The addition of organic compounds, such as PEG, EG into suspension solution for improving critical current density was investigated. Surface state, deposition condition, pore distribution and cracks were investigated by using SEM photographs. Controlling preparation conditions were studied for reducing these defects. As a results, in acetone solution, the surface crack of samples was decreased with increasing PEG. On the contrary, the surface crack of sample was increasing with increasing the amount of EG. In ethanol solution without I$_2$, which was generally used for an electrolyte, the deposition time was longer than this of acetone. For that reason the sample deposition in ethanol time was needed with enough stirring time for suspending YBCO powder and deposition time.

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Control of Cracking on Superconducting Wire by Electrophoresis (전기영동 초전도 선재의 크랙발생 억제)

  • 소대화;이영매;조용준;김태완;박정철;코로보바나탈리아
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2000.07a
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    • pp.270-273
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    • 2000
  • For the well-preparation of the superconducting wire by electrophoresis, the control of the cracking on the YBCO, BSCCO superconductor deposited on Ag wire in acetone and buthanol solution with PEG(poly-ethylenglycol) was investigated with XRD and SEM analysis. After deposition, drying and heat treatment process, the cracks on the deposited surface of YBCO and BSCCO samples was clearly removed and decreased, which was perpared in suspension with addition of PEG from 1 to 3ml. However, in the case of the addition rate of PEG in acetone suspension was exceeded in 3ml, BSCCO superconductor deposited on Ag wire was slightly melted at 90$0^{\circ}C$ which was the same heat treatment condition of other samples with different additin rate of PEG. In the process of electrophoretic deposition, drying and heat treatment, PEG added into the suspension solution as a binder was very useful to prepare the crack-free thick film-wire of YBCO and BSCCO.

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Development of {110}<110> Textured Ag Substrate for YBCO Coated Conductors ({110}<110> 집합조직을 가지는 YBCO 박막 선재용 Ag Substrate 개발)

  • 임준형;김정호;지봉기;장석헌;김규태;주진호;김찬중;홍계원
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.17 no.1
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    • pp.94-100
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    • 2004
  • We fabricated textured Ag substrates for YBCO coated conductor and evaluated the effects of annealing temperature on microstructural evolution, texture formation, and surface morphology. Ag ingot, as an initial specimen, was prepared by plasma arc melting(PAM). Subsequently, the ingot was cold rolled to 100 ${\mu}{\textrm}{m}$ thick tape and annealed at temperatures of 600-80$0^{\circ}C$. The texture and surface morphology of the substrate were characterized by pole-figure and atomic force microscopy(AFM) profile, respectively. It was observed that a strong {110}<110> texture was formed after annealing and its symmetry improved as annealing temperature increased. The full-width at half-maximum(FWHM) of {110}<110> pole was as sharp as 10$^{\circ}$ for the substrate annealed at 80$0^{\circ}C$. On the other hand, it was found that the thermal grooving and faceting became remarkable as annealing temperature increased : root-mean-square(RMS) roughness of the substrate annealed at 80$0^{\circ}C$ was 39.2 nm. The substrate of strong texture and smooth surface, fabricated in our study, is considered to be suitable for use as a substrate for the epitaxial deposition of superconductor film.

Quench Characteristics of Resistive Superconducting Fault Current Limiters (저항형 초전도 한류소자의 퀜치 특성)

  • Kim, Hye-Rim;Hyun, Ok-Bae;Choi, Hyo-Sang;Hwang, Si-Dole;Kim, Sang-Joon
    • 한국초전도학회:학술대회논문집
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    • v.9
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    • pp.214-217
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    • 1999
  • We investigated the quench characteristics of meander line type resistive superconducting fault current limiters based on YBCO thin films grown on 2" diameter LaAlO$_3$ substrates. A gold layer was deposited onto the 0.4 ${\mu}$ m thick YBCO film to disperse the heat generated at hot spots, prior to patterning into 1 mm wide meander lines by photolithography. The limiters were tested with simulated fault currents of various amplitudes. The quench started at 10 A and was completed within 1 msec at the fault current of 65 A$_{peak}$. The dynamic quench characteristics were explained based on the heat conduction within the film and the heat transfer between the film and the surrounding liquid nitrogen. The heat transfer coefficient per unit area was estimated to be 3.0 W/cm$^2$K.

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Electrophoretic Deposition Technique by Vertical Lateral Assisted Field (측면수직보조전계에 의한 전기영동전착 기술)

  • Soh, Dae-Wha;Jeon, Yong-Woo;Park, Jeung-Cheul;Fan, Zhanguo
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.05b
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    • pp.82-85
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    • 2003
  • This dissertation describes an optimization method for fabricating thick films with superconducting YBCO powders by electrophoresis technique. The lateral alternating applied voltage caused to shake the superconducting powder vertically to the deposition field during the process of the oriented deposition so that it was deposited along the c-axis on the silver tape with shaky-aligned EPD. As the result, the optimized thin film fabrication method was obtained to get more dense and uniform surface morphology as well as the improved critical current density. For commercial utilization and efficiency, in this dissertation, alternating voltage of 25-120 V/cm in frequency of 60Hz was proposed to apply it as a subsidiary source for shaky-flow deposition so that the fabricated thin film showed uniform surface morphology with less voids and cracks and $T_{c.zero}$ of 90 K and the critical current density of $3419A/cm^2$.

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A study on characteristics for a resistive SFCL with gold layer (Gold층을 가진 저항형 초전도 한류기에 대한 특성연구)

  • Choi, Hyo-Sang;Hyun, Ok-Bae;Kim, Hye-Rim;Hwang, Si-Dole;Kim, Sang-Joon
    • 한국초전도학회:학술대회논문집
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    • v.9
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    • pp.348-351
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    • 1999
  • We investigated current limiting properties for an SFCL of YBCO thin film coated with an Au layer. The YBCO film of 1 mm wide and 400 nm thick could carry the current 9.6 A$_{peak}$ without quench. The SFCL limited the fault current below 7.6 A$_{peak}$, which otherwise increases above 65 A$_{peak}$ and melted down at the potential fault current of about 100 A$_{peak}$ which is 10 times greater than the quench current. This means that the Au layer successfully protected the superconducting film by dispersing the heat generated at hot spots and electrically shunting the YBCO film.

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Superconducting Thick Film by Lateral Field Assisted EPD (측면보조전계 인가 전기영동전착 초전도후막)

  • 전용우;소대화;조용준
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.8 no.3
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    • pp.679-685
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    • 2004
  • Although the electrophoretic deposition method has the advantage of simple processing procedure, less fabrication facilities, and easier control for deposition thickness and wire length, providing economical and technical merits, it also has the disadvantages of cracking and porosity phenomena, requiring an improved processing method for higher particle density and constant particle orientation. we have developed an optimization method to increase the particle density and to unify its orientation, and have performed a study to overcome the cracking and porosity problems in the fabricated superconductor. In order to improve the surface uniformity and the conduction properties of the fabricated YBCO thick films, a system that applies alternate voltage vertically has been developed for the first time and applied to the electrophoretic deposition process. The applied alternate electric field caused a force to be exerted on each YBCO particle and resulted in a rotation of the particle in the direction of applied electric field, accomplishing a uniform particle orientation. We name this process as the shaky-aligned electrophoretic deposition method. For commercial utilization and efficiency, in this dissertation, alternating voltage of 60 Hz and 25 ∼ 120 V/cm was proposed to apply it as a subsidiary source for shaky-flow deposition so that the fabricated thin film showed uniform surface morphology with less voids and cracks and Tc,zero of 90 K and the critical current density of 3419 A/$cm^2$.

Fabrication and Characterization of High $T_c$ $YBa_2Cu_3O_7-x$ Thick Films (YBCO 고온 초전도체 후막의 제작 및 특성 연구)

  • 정형진;박홍순;이전국;송진태
    • Journal of the Korean Ceramic Society
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    • v.27 no.3
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    • pp.299-310
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    • 1990
  • The fabrication of Y-Ba-Cu-O films and experimental factors affecting to characteristics of films are studied in detail. Superconducting thick films are fabricated by the screen printing method. The metal-citrate precursors are obtained simply by mixing of metal nitrate with citric acid. The particle size of heat treated powders is approximately 0.3-1${\mu}{\textrm}{m}$ and the thickness of film is estimated as 30-35${\mu}{\textrm}{m}$. According to the XRD analysis, the films sintered at 870-93$0^{\circ}C$ for 10min. -6hr with P(oxygen)=1atm has the unique orthorhombic crystal symmetry indicating the 123 phae. Tc, onset is determined around 92-87。K, but it shows semiconducting behavior probably due to the oxygen deficiency in the lattice, porosity and impurities in films. Extrapolated Tc, zero is estimated as 76-50。K. For films sintered at 90$0^{\circ}C$ for 1hr, superconducting properties are observed with the room temperature resistivity of 0.025$\Omega$.cm Tc, onset at 88。K and Tc, zero at 63。K.

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Design and Characterization of HTS antenna array with sequential rotation array (순차적 순환배열을 이용한 고온초전도 배열 안테나 설계 및 특성해석)

  • Chung, D.C.;Hwang, J.S.;Kim, Y.M.;Choi, H.S.
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2006.05a
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    • pp.77-81
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    • 2006
  • We report the performance of a four-element, 11.67 GHz, high-Tc superconducting (HTS) microstrip antenna array with corporate feed network and circular polarization for direct broadcasting satellite (DBS) system. Our array antennas were designed and built on a 0.5 mm thick MgO substrate. To compare the superconducting antennas with normal conducting counterpart, One antenna pattern was fabricated from gold thin film, and a second pattern was fabricated from $YBa_2Cu_3O_{7-x}$ (YBCO) superconducting thin film. To improve the axial ratio of circularly polarized arrays, sequential rotation technique were used. Efficiency, radiation pattern, return loss and bandwidth were measured for both antennas at room temperature and at cryogenic temperature. The array produced good circular polarization, and the gain of the array at 77 K, relative to a copper array at room temperature was approximately 1.54 dB. The measured return loss of our HTS antenna array was 35.79 dB at the resonant frequency of 11.67 GHz and The total effective bandwidth was about 3.4 %. The results showed that high-temperature superconductors, when used in microstrip arrays, improved the efficiency of the HTS antenna array for circularly polarization.

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